<!DOCTYPE html>
<script src='../../resources/gesture-util.js'></script>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>

<style>
#blue {
    background-color: rgb(0, 0, 255);
    position: absolute;
    left: 75px;
    top: 75px;
    height: 100px;
    width: 100px;
}
#blue:hover {
    top: 500px;
}
</style>
<div id="blue"></div>
<script>
const x = 100;
const y = 100;
var blue = document.getElementById('blue');

window.onload = async () => {
  promise_test(async () => {
    // Move the blue element away when it is hovered, so the blue element will oscillates
    // between 75px and 500px at each animation frame.
    await mouseMoveTo(x, y);
    // When the blue element is hovered, it will moved to 500px from the top.
    await waitFor( () => { return blue.matches(':hover');}, 'wait for move to the blue element');
    assert_equals(blue.offsetTop, 500, "Check that the blue element is moved to 500px from the top");

    // When the blue element is not hovered, it will set to its default position.
    await waitFor( () => { return !blue.matches(':hover');}, 'wait for move to the blue element');
    assert_equals(blue.offsetTop, 75, "The blue element is moved back to 75px from the top");
  }, 'The hover state is updated at the begin frame after the layout changes which is caused by hover update.');
}
</script>